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V – I graph for two… (Class 10 Science 2023, Q25)

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ScienceCBSE Class 10 · Board exam 2023, set 31/2/1 · 2 marks · Very short answer

CBSE Class 10 Science 2023: question 25

Set in the CBSE Class 10 board exam of 2023, paper 31/2/1, section B, question 25, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q25 · 2 marks · Very short answerCompetency-basedElectricity

V – I graph for two conducting wires A and B are as shown. If both wires are of the same length and same diameter, which of the two is made of a material of high resistivity ? Give reasons to justify your answer.

Figure in the paper: V–I graph with V on the vertical axis and I on the horizontal axis. Two straight lines start from the origin: line B is steeper, and line A has a smaller slope (lies lower, closer to the I-axis). Both are labelled. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/2/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

What physical quantity does the slope of a V–I graph represent?

Hint 2

Write the formula connecting resistance with length, area and resistivity.

Hint 3

If l and A are fixed, how are R and ρ related?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. With V on the y-axis and I on the x-axis, the slope of each line gives . Line B is steeper, so . Wire B is made of the material of higher resistivity.

    1 mark

  2. Resistance is . Both wires have the same length and the same diameter, so the same area . Hence . The wire with greater resistance (B) must have the greater resistivity.

    1 mark

Answer: Wire B

Where the marks are

  • Identifies wire B (greater slope means greater resistance) (1 mark)
  • Justifies using R = ρl/A: for the same dimensions, greater resistance means greater resistivity (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Electricity, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/2/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.